Pressure indicator



Dec. l, 1931. P. M. STIVENDER PRESSURE INDICATOR Filed Feb. 5, 1929 inautomotive vehicles. The invention mayA Patented Dec. 1, 1931 UNITED gSTAT-Es PAUL M. STIYENDER, 0F WEST ALLIS, WISGQNSIN Yrmassuitn INDICATORApplication led February 5, .1929. Serial No. 337,605'.

This invention relates to fluid-pressure indicators. One embodiment ofthe invention is particularly applicable to the indication of the airpressure in pneumatic tires as used also be utilized for the indicationof hydro-- static head and the like.

@ne of the objects of the invention is the provision of an indicatorVwhichlhas what may be termed a critical point, that is, an

abruptfchange in its indication is produced when the fluid mined value.

Another object isthe provision of an indipressure reaches a' predeteraglance, Without the reading of graduations and the like and Withoutclose inspection,

Whether a tire is in need of air. 'l A. further object is the provisionof an indicator which maybe read With equal facility nomatter What theposition of the tire valvestem may be, and more specifcallywhicli may beread by a person in a standing position in the neighborhood of thevehicle Wheel.

Other objects will appearhereinafter as the description of the inventionproceeds.

The novel features of the invention will appear from this specificationand the accom- 'i panying drawings forming a part thereof anddisclosing` several embodiments of theinvention, and all these novelfeatures are intended to be pointed out in the claims.

In the drawings Fig. l is a sectional elevation of a pressure indicatorembodying the invention.

Fig2 is a section along the line II-II of Fig. l.

Y.. Y i ig. 3 isa similar section but with one of the parts inV adifferent position.

Fig. 4 is a part sectional elevation of another form of pressureindicator embodying the invention.

Fig. 5 is a detail view of a portion ofthe -f forni of indicator shownin Fig. 4, Witlithe parts in a-dilferentjpositionf modified indicators,and'FigL Sis a detail of modified form, I

cater which may be permanently connected to a pneumatic tire andWhichwvill indicate atv will `be hereinafter set forth.

.s igs. 6 and 7 are fragmentary vievvs'ofk 1 Referring to Fig. kl 'offthe' drawings, the( pressure indicator as here shown includes 'achamber l indicated as being made'of a glass tube in part.` Othersuitable materials such as Celluloid, phenolic condensation productsetc. may-be utilized if desired. The chamber lalso includes a iexibleWall 2 which may be a rubber bagi-likememberor metal bellows disposedabout the end .ofthe glass tube 1.

The glass tube ly is here shown as having its end formed with a smallbead to better hold the flexible Wall 2 in position.

The lchamber 1 hasdi'sposed thereiiifafl'oat or" diver?) whichV is hereshown, as may be seen best from Fig. 2, as including a flexiblebag-likemember 4, in this instance containing air, and. sealedinanyfsuitable'manner. The bag-like member 4 thus constitutes a memberwhich Will have its volume decreased under Aincreased pressure and-Willreturn to its original volume when the original pressure obtains. Thebag 4Lisfcemented or fastened inany suitable'manner to the inside of thediver 3 and as indicated in Fig. 2 iseccentificlivitliv the diver3.. Thefloat Vor diver therefore Willbe' disposed in a liquid 5 with` l whichthe chamber l is lilled,`witli4 a definite side upward at all times, fora purpose lWhich.

' The chamber l may be heldin a tubular member means of cement 7Thetubular member 6 is here shown as having a criiiipfedr portion vS tobetter vhold the chamber l. 2The tubular'member 6fis provided with a,-neck 9 having a lpassagelO. VThe neck 9'may be 4applied in; any suitablemanner to the source ,of fluid under pressure, the pressure' of Which isto be indicated. In this instance the neck 9 is shown as applied to thevalve stem of a pneumatic tire, by means of anniversal screw joint vl2,a gaskety 13 being provided tovinake the joint airtight. The valve stem1l contains the usual vaglve core or inside' 14. Theneck 9 is providedas here shownyi-ii the passage '10, with a plug 15 provided with achannel as indicated on the right hand side of the plug. The plug 15' isfor the purposev of depressing the stem ofthe valvecoreto open the'valveWhen-the neck 9 isfappliedito the valve stem 1v1, thereby'openingcommunication between the source of fluid pressure and the inside of thetubular member 6.

The tubular member 6 is here shown as provided with an elbow pipe 16having a passage 17 communicating with the interior of tubular member 6.The elbow pipe 16 is provided with a valve core 18 which is normallyvclosed.

` A tire valve VVcap 19 may be provided for the end of the pipe 16. Ashereshowntlie pipe relieve the pressure on the bag-like member 4 16 maybe joined to the tubular byaweb20. Y. m'

Assuming the pressure indicator to be apmeniber 6 plied to a tire valvestem as showny in-'Figu 1 and the valve 18 to be closed, the airpressure within the tubular member 6 is the samel as that within thetire and acts against the flexiblelwall 2 thereby placing the liquid 5under compression. The compression on the liquid 5 in turn compressesthe bag-like member 4 and the air therein thereby decreasing the volumeand therefore the buoyancy of the float or diver as a whole.Y Atapredetermined presf sure the diver 3 sinks inthe liquid 5. The diver isshown in Figs. 1 and 2, as not .quite on thebottom of the chamber, butitis so delicately poised thatit will sink to the bot.

tom of the chamberV once it starts to sink under apredeterminedpressure.Whenthe pressure in the tire decreases, the consequent reduction 'ofpressure the flexible wall '2.will

thereby permitting the air therein to expand andthe consequent increasein buoyancy will cause the diver to rise to the position shown in Fig. 3in which the'diver is in contactwith the wall of the chamber 1. It hasbeenfound that with a predetermined desired pressure against theflexible wall 2, only avery slight reduction in pressure is required tocause the diver to rise to the position asshown in Fig. 3

' in which the red indication is given.

In order to better show the state of pressure of the'air in the tire,the liquid 5 jmay be blue, for example, and the ydiverinay have itsupper portion coloredred and itsk lower It is however not essentialportion blue. that the upper and lower portions of the diver be ofdifferentcolors. When the diver 3 is in the position shown in Fig.2 itisinvisible for the'reason that the red portion thereof does not showthrough the blue liquid. When,

'the valve stem 11 soA tliatthe axis of the chamber 1 is parallel totheaxis of the wheel (not shown). always disposed in the liquid 5'with avdefinite s idevuppermost it is immaterial whether the Inasmuch as thediver 3 isA valve stem 11 is projecting downwardly, upwardly or in factin any radial direction from the wheel rim; the red portion of the diverwill always be presented toward an observer standing next to the wheeland looking downwardly at it.

Referring now to Fig. 4, the pressure indicatorhere shown includbes achamber 21 which may be of metal, provided with a glass win- Vdow`22.The chamber 21 has its walls disposedabout a tubular. member 23. The endof the tubular member 23 has stretched across it a rubber diaphragm 24.The chamber walls 21 may be fastened to the member 23 by means of cement25. The space 26 is filled with a liquid. The color of the liquid andthat of the diaphragm 24 are preferably different, the `liquid being,for example, red and the diaphragm-blue. o

Thetubular member .23 has an enlarged portion 27 in threaded engagementwith a boss 28. The boss 28 has a passage 29 which communicates with aflexible member indicated as a rubber bag 30. The rubber bag issurrounded by means of a vspring 31 here shown as having an enlargedturn disposed betweenthe shoulder formed by the enlarged portion V27 andan outwardly extending portion `32 of thev rubber bagv30.V The tubularmember 23xthereffore serves to hold the bag and springk31 positionagainst the boss The springl 31 has a few turns of reduced diameter atthe right hand end thereof as viewed in Fig. 4, Vand these turnssurround a reduced portion 34'o'f a plunger 33 which is; i'njengagementwith the end of the rubber bag 130. Y V Y .The boss 28 Vis shown asassociated with a pipe 35 having a passage 36 communicating with thepassager29. A portion 37 of the pipe 35 also communicates with thepassage 36 and may contain a valve similar to the valve 18 in Fig. 1.Thepipe 36 is of course adapted to be applied ,to a source Vof pressurein thesame manner as described in connection with Fig. 1. l 5 v Whenthere is a predetermined fluid pressure within the bag 30 the plunger 33is moved againstV the rubber diaphragm 24 thereby forcing the head 34 ofthe plunger against thel diaphragm, pressing the diaphragm -against Vtheinside of the glass window 22.

Looking'toward the window 22 the observer will then see a bluerspotsurrounded by a red border, assuming the diaphragm to be blue and theliquid red. It i-s of course apparent that other color combinations maybe chosen. Upon reduction in pressure within the bag 30 to apredetermined amount the plunger head 34 will permit the diaphragm 24 toleave the windowv 22 thus permitting the red liquid to again 'lowinto.the space between the window and the diaphragm. The blue spot istherefore no longeryisible and this at once gives an indicationofthelack of proper pressure in the tire. i

It will be apparent that the indication given in the form ofithe`invention 'shown in F ig. 4 is also very readily visible to a personstanding in the ,neighborhood ofL the wheel to which it may. be,applied, no matter what the position of the valve stem may be.

Referring to Fig. 6 this shows modified parts which maybe used inplaceof certain parts of the deviceillustrated in Fig. 1. The chamber 1acorresponds tochamber 1 in Fig. 1 and contains a diver 3,.` The chamberis providedwith a flexible metal or rubber wall 2a which in the instanceshown is held infposition bymeans of a suitable Vplug 38 provided withone or more small passages 39. The

' spaces 40 and 40,L within the wall 2a and chamber proper 1 are filledwitha liquid.- Pressure placed upon the wall 2a places the liquid inspace 40a under pressure and the operation is as already described inconnection with Fig. 1. If the chamber 1a shouldfbreak,

the air in the tire, to which the pressure responsive device may beapplied, will not be lost because the wall 2, willl be stopped by theplug 38, and cannot blow-out even if made ofrru ber, through the smallopening 39.

The diver 3,l is of modified form and may ofcourse be utilized in placeof the diver 3 of Fig. 1. Itis here shown as made of a sealed metalbellows 41 which isadapted to decrease and increase in volume either byreason ofits own resilience alone or because of air or other gas, or aquantity of volatileliqui'd such as other, or alcohol, containedtherein. The bellows 41 may be mounted within a cylin' der 42 which ishere.shownasconcentric with the bellows 41. In thiscase the indicatingcolor on thecylinder. may extend uniformly completely around the samebecause there is'little tendency for the Adriver to present the sameportion of its surface upwardly'at all times. The cylinder 42er bellows41 maybe made quite large compareduto the inside diameter of the chamber1a, so that a large portion of its colored-surface will be visible whenit is in contact with-the chamber wall. rIhe cylinder 42 may be omitted,`and the bel# lows colored.

` vA modified form of diver `is-illustrated'in* Fig. 8. Thediver .hereshown comprises a rubber tube 49 the ends of which are sealed bv rubberdiscs 50 cemented in place. Vithm the tube 49 is disposed a spring 51made of Celluloid` or 'other suitable vmaterial.l The spring maintainsthe form of the tube 49 but permits it to be compressed longitudinally.

The spring thus servesto return the diver to itsV original volume whentheV pressure 1sl removed' independently of any gas `in the tube.V Theendwalls of the 'diver may be stren'gthenedby discs of celluloid 52, forexample, which may be held in pjositionbyrubber discs 53 cementedfmplace. f.

suitably held to the open end of chamberzlb. K

A plunger 44 is disposed inthe chamber, and has a conical orwedge-shaped end adapted to approximately fit the endk of the chamber.Theplunger has a stem 45 which is suitably fastened to the wall 43 andmay if desired pass through said wall as shown. If the stem passes.through the wall it may be fastened thereto by a liquid tight joint asby ymeans of a clamp 46. rlhe plunger maybe provided withv a smallpassage 47 ywhich places bodies vof liquid to the right and lleft of theplunger in communication. When the wall 43 is placed under pressure theplunger is moved to the right until it contacts with the chamber wallthe liquid being displaced. Thefportion 48ofthe plunger (or the entireplunger) may be ofa differ-- entv color from the liquid so that underthe stated conditions the surface 48 is visible in contrast .to theliquid. When the pressure decreases to a predetermined amount the exiblewall draws the plunger toward the left and thercolored liquid flows tothe right 1 through passage 47 thereby again covering the surface 48 ofthe plunger.

It .will be apparent that in the forms of the invention illustrated theindicator has in the forms utilizing a diver as set forth. Also becausethe indication is given by a member between which and the wall withwhich Vit substantially contacts, there is a thin film of liquid whichseems to exert an adhesion effect, so that the motion of the member awayfrom the wall is comparativelyabrupt. Alsovery little motion isnecessary because only a small layer of colored liquid is necessary tocause the dissimilarly colored member to disappear from view.

It should be understood that it is not desired to limit the invention tothe exact 'details of construction shown and described, for obviousmodifications may occur .to personsskilled in the art.- n

It is claimed and desired to secure by Letters Patent: i Y y, f

1. Afluid pressure indicator including a closed chamber containing aliquid, a 'Second chamber, means `for lplacing in` communication withsaid second chamber the fluid the pressure of which is to be indicated,and means including a flexible wall for said first named chamber exposedto the action of the fluid under pressure in said second chamber for-indicatingthe-degree of said pressure.V .V

2. A fluid pressure indicator including,

a closedchamber containing a liquid, .a secs. x

a critical point. This is particularly marked ond chamber, vmeans forplacingV in communication'with said second chamber the fluid thepressure of which is to be indicated, andA means including a'flexiblewall for said first named .chamber serving as one Wall of said secondchamber for indicating the degrec of said pressure.

In a fluid-.pressure indicator, a body o colored liquid, a transparentWall forming a boundary for said liquid, and means movable with respectto said wall subjected to the fluid under pressure for displacing theliquid away from said wall to thereby make the degree of said pressurevisible.

4. In'a fluid-pressure indicator, a .body of colored liquid, atransparent wall forming aboundary for said liquidand`means.sub jectedto the fluid under pressure including a member khaving a color differentfrom said liquid movable with respect to said Vwall whereby said vmemberis visible when the pressure is above a predetermined amount and isinvisible when the pressure is below a predetermined amount.

'5. A fluid pressureindicator including, a closed chamber containing aliquid, a second chamber, means for placing vin communication with saidsecond chamber the fluid the lp pressure of which is to be indicated,and

means for indicating the degree of said pressure including a flexiblewall for said first named chamber and a buoyant member disposed in saidliquid, the buoyancy of which member depends. upon the pressure uponsaid flexible wall.

. 6. A fluid pressure indicator including, a closed chamber containing aliquid, a second chamber, meansY for placing in communicationwith saidsecond chamber the fluid the pressure of which is to be indicated, andmeans for indicating the degree of said pressure including a flexiblewall forv said first named chamber anda buoyant member disposed in saidliquid comprising acompressible and expansiblc member whereby the amountof liquid it displaces varies with the pressure on said flexible wall.

, 7. A fluid pressure indicator for pneumatic vehicle-tires, including achamber having a transparent wall, said chamber having a longitudinalaxis parallel to the axis of the tire, a second'chamber, -meansforsupporting said chambers from the valve stem of thetire and forvplacing said second chamber in communication with the'inside of saidtire, and means whereby the state of air pressure .in vsaid 'secondchamber isY made visible through said transparent wall. e

1 8. In afluid-pressure indicator, a chamber containing a liquid andhaving a transparent wall and a flexible wall, means whereby saidflexible wall is exposed to the fluid'underpressure, means including abuoyant member disposed in said liquid, the buoyancy of Which memberdepends upon the pressure upon said flexible wall, and means forweighting said buoyant member so that it is disposed in said liquid witha predetermined side uppermost, the color of said upper side beingdifferent than that ofsaid liquid. `9. In a fluid-pressure indicator, achamber containing a colored liquidV and having a transparent wall and aflexible wall, means whereby said flexible wall is exposed to the fluidunder pressure, anda buoyant member disposed in said liquid, the`buoyancy of which member depends upon the pressure `on said flexiblewall, at least a portion of said buoyant member being coloreddifferently from said liquid.

10. In a fluid-pressure indicator Vof the type described, a buoyantmember comprising a compressible and expansible sealed bellows-likecorrugated metal capsule.

f 11. In a fluid-pressure indicator of the type described, a buoyantmember comprising a com'pressible and expansible member including asealed flexible capsule, and a spring disposed within said capsule.

12. VIn a fluid-pressure indicator, a chamber containing a coloredliquid and having a transparent wall, means whereby said liquid isexposed to the pressure to be indicated, andV a buoyant member disposedin said 1iquid,.the buoyancy of which member depends upon said pressure,at least a portion of said buoyant member being colored differently'fromsaid liquid.

13. In a fluid-pressure indicator, a chamber having a transparent walland a flexible wall, means including a fluid in said chamberforrendering the degree of'pressure on said flexible wall visiblethrough said transparent wall, and a partition'between said chamberwalls, said partition having a predetermined number of openings servingto put'the bodies of fluid on opposite sides of said partitionincommunication.

14. `In a fluid pressure indicator, a closed chamber containing a fluid,means whereby an exterior portion of said chamber is exposed to thefluid under pressure, and means including a flexible Wall for saidchamber at said exposed portion of said chamber for indicating thedegree of said pressure.

15. In a `fluid pressure indicator, a body of liquid, means for placingsaid liquid under pressure, and hollow vhermetically sealed buoyantmeans disposed in said liquid, said means including at least one Walladapted to flex under pressure on said liquid to thereby alter thebuoyancy of said means.

1.6. In a fluid pressure indicator, a body of liquid, means for placingsaid liquid under pressure, and hollow hermetically sealed buoyantmeansdisposed in said-liquid, said means including at least one pair ofapproximately parallel .walls adapted to flex under` pressure on; saidliquid to thereby alter the buoyancy of said means. c

17. In a fluid pressure indicator, a body of l liquid, means for placingsaid liquid under pressure, and hollow hermetically sealed buoyant meansdisposed in said liquid, said means including a plurality of cells eachcell having at least one wall adapted to ieX under pressure on saidliquid to thereby alter the buoyancy of said means.

18. In a iuid pressure indicator of the type described, a buoyant membercomprising a compressible and eXpansible sealed corrugated capsule.

19. In an indicator, a body ofcolored liquid, a transparent wall forminga boundary n for said liquid, and means movable with respect to saidwall for displacing the liquid away from said wall to thereby makevisible said movement of said means.

20. In an indicator, aL body of colored liquid, a transparent wallforming a boundary for said liquid, a member having a surface submergedin said liquid and facing said wall said surface having a colordifferent from said liquid, and means for moving said surface intoengagement with said Wall to thereby make said surface visible.

In testimony whereof, the signature of the inventor is affixed hereto.

PAUL M. STIVENDER.

